There is an increasing need to support efficient and cost-effective devices, or terminals, in a cellular communications network. This is especially true with the increasing interest in and development of Machine-to-Machine (M2M) communication. In the 3rd Generation Partnership Project (3GPP) standards, unlike traditional services such as voice and web streaming, M2M services often have very different requirements on the cellular communications network due to specific features of M2M services specified in 3GPP Technical Specification (TS) 22.368 V11.6.0, “Service requirements for Machine-Type Communications (MTC); Stage 1.” Another distinguishing characteristic in a cellular communications network with M2M communication is the large increase in the number of Machine Type Communication (MTC) devices. Both the different requirements of M2M services and the large number of MTC devices bring forth new challenges to develop a cost, spectrum, and energy efficient radio access technology for M2M applications and MTC devices in a cellular communications network.
In M2M communications, the MTC devices (e.g., smart meters, signboards, cameras, remote sensors, laptops, and appliances) are connected to the cellular communications network. Most of the MTC devices sporadically transmit one or only a few short packets containing measurements, reports, and triggers, e.g., temperature, humidity, wind speed, etc. In most cases, the MTC devices are expected to be static or to have low mobility. A common understanding of MTC devices is that the MTC devices should be of low complexity targeting low-end (low average revenue per user, low data rate, high latency tolerance) applications. The power/energy consumption of the MTC devices is expected to be low as well.
Several factors affect the cost for both manufacturing and operating a given wireless device. The main manufacturing cost drivers are: (1) processing speed (mainly at reception), (2) number of antennas, and (3) bandwidth. Therefore, 3GPP Radio Access Network (RAN) Work Group 1 (i.e., RAN1) has studied Long Term Evolution (LTE) User Equipment (UE) modem cost reduction techniques for provisioning of low-cost MTC UEs based on LTE. The results of the study are documented in 3GPP Technical Report (TR) 36.888 V2.0.0 (3GPP Tdoc RP-120714), “Study on provision of low-cost Machine-Type Communications (MTC) User Equipments (UEs) based on LTE.” Since then, an updated Study Item Description (SID) (3GPP Tdoc RP-121441, “Study on Provision of low-cost MTC UEs based on LTE”) has been approved which extends the scope of the study to also include study of coverage enhancements. More specifically, the updated SID states that:                A 20 dB improvement in coverage in comparison to defined LTE cell coverage footprint engineered for “normal LTE UEs” should be targeted for low-cost MTC UEs, using very low rate traffic with relaxed latency (e.g. size of the order of 100 bytes/message in UL and 20 bytes/message in DL, and allowing latency of up to 10 seconds for DL and up to 1 hour in uplink, i.e. not voice). In identifying solutions, any other related work agreed for Release 12 should be taken into account.        